Would you, as a founder, be comfortable if your fulltime employee works freelance elsewhere (not a competitor)?

I've worked with 3 startups so far and always had freelance clients on the side. Not once has this hampered my results for my main priority - my fulltime job. My employers who didn't know about this were always pleased with my results (I've always delivered growth and smashed my KPIs - delivering numbers like 30% open rates on email newsletters, showing attributed SQL increase and three figure percentage social growth) but the 1 employer that knew about my side hustle was never happy with me despite managing a big team and crushing it at work. Berated me to the point that I had to quit and I've heard since then my successor has been fired and a new person is already in that role - all this 2 months since I left. What's going on in your mind as a founder when you find out your employee works with other clients (not competing in your niche)?